The disposal of solid waste materials has become a major problem for both public and private organizations. Recycling programs have successfully used only a portion of this waste stream, however. The vast majority of waste streams are either burned or introduced into landfills.
Throughout the built environment, the amount of solid waste generated by individual households, businesses and governmental units has substantially increased over the last ten years. Disposal of such waste materials has become an increasingly difficult problem for both private and public organizations. The convenience and cost of waste disposal has steadily increased along with the environmental impact of the solid waste on land use, portable water and the atmosphere of the natural environment.
Recycling efforts have had some success; however, the major proportion of recyclable materials is not recycled and remains as solid waste. In order to obtain valuable materials, solid waste materials have been treated or pretreated. None of these pretreatment processes has been widely accepted in view of the relatively high cost and low efficiency of solid waste separation processes. One attempt to introduce apparatus Systems and processes for treating waste material to form a useful fuel and a glass, a metal or other recyclable streams is found in Anderson, U.S. Pat. Nos. 5,445,329, 5,540,391, 5,655,718 and the related PCT WO 95/13148 and also in Garrison et al., PCT WO 00/72987. These references disclose apparatus, methods and processing of municipal solid wastes into fuel and recyclable streams such as a glass stream, a metal stream and a plastic stream if implemented.
These processes involve an apparatus that can be used to treat solid waste material. The waste material is placed into a vessel, contacted with steam and processed at increased temperature and pressure. The variety in moisture, temperature and pressure within the vessel contacting the solid waste under conditions of rotary agitation can cause the solid waste product to break down into a useful burnable solid fuel and can also result in formation of easily separable metal, glass and plastic streams that can be readily removed from the solid fuel material using conventional separation techniques based on magnets, density and particle size-type separating systems such as a trommel or flat bed separator.
The vessel used to treat the solid waste requires the application of pressure to successfully treat the solid waste efficiently. The pressure, up to 600 psig (about 4200 kPa), about 60 psig (about 410 kPa) or as little as 10 psig (about 100 kPa), can be maintained within the vessel between charging and discharging the vessel using a closure system. The prior art apparatus and processes, while adequately treating the solid waste for the purpose of obtaining fuel and separable recyclable stream, have their productivity reduced by the difficulty in attaching the closure after charging and then removing the closure from the vessel for the purpose of discharging the treated waste. A variety of prior art pressure vessel closure systems have been disclosed. Representative patents include King, U.S. Pat. No. 3,107,810, that shows a rotatable tab system that can be used to seal a high pressure autoclave. FIG. 1 of King shows door 14 and lugs 18 and 19. These lugs 18 and 19 are slanted in order to cause the door to seal against the frame. Hersman, U.S. Pat. No. 2,989,209, discloses a unique flexible polygonal gasket that under pressure forms a seal in the structure. See FIGS. 4 and 5 of Hersman and the movable polygonal gasket structure. Bowman, U.S. Pat. No. 2,196,895, shows a segmented structure driven by a mechanical screw mechanism. FIG. 3 of Bowman shows the ring in a retracted position, while FIG. 2 of Bowman shows the ring in an expanded position. Bowman uses a non-continuous segmented closure structure that uses a bolt-like threaded member to advance and retract each segment to affect the seal. The screw causes the diameter of the circular member to increase or decrease in diameter to effectuate the seal. Platts, U.S. Pat. No. 4,102,474, shows an expandable door lock/closure mechanism. As shown in FIG. 1 of Platts, the structure includes a number of blocks 8 that can be moved from a locking position to an unlocked position or from an unlocked position to a lock position forming a “nearly complete ring” to seal the door. Multiple blocks 8 are moved by hydraulic cylinders 50 and place the blocks into locking position. Reneau, U.S. Pat. No. 4,489,850, also shows a segmented seal structure that can be moved radially to seal the door. The door seals shown in FIG. 1 of Reneau at 16a through 16f are moved by locking pawls P that push the member into a locking position. This mechanism is somewhat similar to the mechanism in Bowman, however, it uses a relatively complex pawl driven movement system made unnecessary by the simple structure of the present invention. Other patent references include, Placzek, U.S. Pat. No. 4,974,781, which shows a discharge door 60, as aspects of a pressure vessel. Anderson, U.S. Pat. Nos. 5,445,329, 5,540,391 and 5,655,718, shows vessel supports 64 and docking ring 180 in FIGS. 6, 16 and 19. Koenig, U.S. Pat. Nos. 6,588,690 and 6,752,337 show a discharge closure for a pressure vessel in FIGS. 1 and 10 and vessel closure 70-72.
In light of the technology disclosed above, a substantial need exists for a pressure vessel closure system having desired properties, while at the same time being configured for ease of use. The pressure vessel closure system should be capable of maintaining a pressure vessel at an internal pressure up to about 30 psi, 206,850 Pa (206.85 kPa) or 60 psi (417.70 kPa), at an increased internal temperature up to at least about 140° C., additionally at a substantial relative humidity, i.e., up to about 100% relative humidity, while being readily moved or removed for discharge and replaced after introduction of solid waste for treatment. The rate at which the closure can be opened and closed can substantially increase productivity, reduce costs and improve the overall quality of the solid waste or recycled streams.